Rock Stars: Then and Now

"I couldn't predict where I was going to end up at the end of the night," he tells the mag in its latest issue.

"I'd wake up in a strange house on a couch. I wouldn't remember how. It was a complete blackout."

At the iHeartRadio festival in Vegas last September, Armstrong went bonkers during a profanity-laced, guitar-smashing rant, yelling, "What the f--k! I'm not f--king Justin Bieber, you motherf--kers," among other things.

Two days later, the singer checked into rehab for what his rep confirmed were substance-abuse issues.

"I remember tiny things," Armstrong says about his infamous Vegas fracas. "The next morning, I woke up. I asked [my wife] Adrienne, 'How bad was it?' She said, 'It's bad.' I called my manager. He said, 'You're getting on a plane, going back to Oakland and going into rehab immediately.'"

The band has since announced new tour dates for this spring, and last December, Armstrong assured fans that he was on the mend as he expressed his gratitude for their support.

"I just wanted to thank you all for all the love support you've showed for the past few months," he wrote on Instagram. "Believe me, it hasn't gone unnoticed and I'm eternally grateful to have such an amazing set of friends and family. I'm getting better everyday."